It's not perfect, but I like my Tamron 90mm macro lens. It's a great macro and portrait lens for the money.

Edit: you can find the older (172E) version on eBay for really cheap, $175 shipped from Japan. http://www.ebay.com/sch/i.html?_odkw=tamron+90mm+macro+canon+172e&_osacat=0&_from=R40&_nkw=tamron+172e+canon&_sacat=0

Edit2: The newer 272E "Di" model can be found for about $250. It's not a vast improvement, it has a different focus grip and it has some kind of less-reflective coating on the back for digital cameras. But in most lighting conditions, there won't be a difference.